arch/s390/kvm/diag.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * handling diagnose instructions
   4  *
   5  * Copyright IBM Corp. 2008, 2020
   6  *
   7  *    Author(s): Carsten Otte <cotte@de.ibm.com>
   8  *               Christian Borntraeger <borntraeger@de.ibm.com>
   9  */
  10
  11 #include <linux/kvm.h>
  12 #include <linux/kvm_host.h>
  13 #include <asm/gmap.h>
  14 #include <asm/virtio-ccw.h>
  15 #include "kvm-s390.h"
  16 #include "trace.h"
  17 #include "trace-s390.h"
  18 #include "gaccess.h"
  19
  20 static int diag_release_pages(struct kvm_vcpu *vcpu)
  21 {
  22         unsigned long start, end;
  23         unsigned long prefix  = kvm_s390_get_prefix(vcpu);
  24
  25         start = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
  26         end = vcpu->run->s.regs.gprs[vcpu->arch.sie_block->ipa & 0xf] + PAGE_SIZE;
  27         vcpu->stat.instruction_diagnose_10++;
  28
  29         if (start & ~PAGE_MASK || end & ~PAGE_MASK || start >= end
  30             || start < 2 * PAGE_SIZE)
  31                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
  32
  33         VCPU_EVENT(vcpu, 5, "diag release pages %lX %lX", start, end);
  34
  35         /*
  36          * We checked for start >= end above, so lets check for the
  37          * fast path (no prefix swap page involved)
  38          */
  39         if (end <= prefix || start >= prefix + 2 * PAGE_SIZE) {
  40                 gmap_discard(vcpu->arch.gmap, start, end);
  41         } else {
  42                 /*
  43                  * This is slow path.  gmap_discard will check for start
  44                  * so lets split this into before prefix, prefix, after
  45                  * prefix and let gmap_discard make some of these calls
  46                  * NOPs.
  47                  */
  48                 gmap_discard(vcpu->arch.gmap, start, prefix);
  49                 if (start <= prefix)
  50                         gmap_discard(vcpu->arch.gmap, 0, PAGE_SIZE);
  51                 if (end > prefix + PAGE_SIZE)
  52                         gmap_discard(vcpu->arch.gmap, PAGE_SIZE, 2 * PAGE_SIZE);
  53                 gmap_discard(vcpu->arch.gmap, prefix + 2 * PAGE_SIZE, end);
  54         }
  55         return 0;
  56 }
  57
  58 static int __diag_page_ref_service(struct kvm_vcpu *vcpu)
  59 {
  60         struct prs_parm {
  61                 u16 code;
  62                 u16 subcode;
  63                 u16 parm_len;
  64                 u16 parm_version;
  65                 u64 token_addr;
  66                 u64 select_mask;
  67                 u64 compare_mask;
  68                 u64 zarch;
  69         };
  70         struct prs_parm parm;
  71         int rc;
  72         u16 rx = (vcpu->arch.sie_block->ipa & 0xf0) >> 4;
  73         u16 ry = (vcpu->arch.sie_block->ipa & 0x0f);
  74
  75         VCPU_EVENT(vcpu, 3, "diag page reference parameter block at 0x%llx",
  76                    vcpu->run->s.regs.gprs[rx]);
  77         vcpu->stat.instruction_diagnose_258++;
  78         if (vcpu->run->s.regs.gprs[rx] & 7)
  79                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
  80         rc = read_guest(vcpu, vcpu->run->s.regs.gprs[rx], rx, &parm, sizeof(parm));
  81         if (rc)
  82                 return kvm_s390_inject_prog_cond(vcpu, rc);
  83         if (parm.parm_version != 2 || parm.parm_len < 5 || parm.code != 0x258)
  84                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
  85
  86         switch (parm.subcode) {
  87         case 0: /* TOKEN */
  88                 VCPU_EVENT(vcpu, 3, "pageref token addr 0x%llx "
  89                            "select mask 0x%llx compare mask 0x%llx",
  90                            parm.token_addr, parm.select_mask, parm.compare_mask);
  91                 if (vcpu->arch.pfault_token != KVM_S390_PFAULT_TOKEN_INVALID) {
  92                         /*
  93                          * If the pagefault handshake is already activated,
  94                          * the token must not be changed.  We have to return
  95                          * decimal 8 instead, as mandated in SC24-6084.
  96                          */
  97                         vcpu->run->s.regs.gprs[ry] = 8;
  98                         return 0;
  99                 }
 100
 101                 if ((parm.compare_mask & parm.select_mask) != parm.compare_mask ||
 102                     parm.token_addr & 7 || parm.zarch != 0x8000000000000000ULL)
 103                         return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 104
 105                 if (!kvm_is_gpa_in_memslot(vcpu->kvm, parm.token_addr))
 106                         return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 107
 108                 vcpu->arch.pfault_token = parm.token_addr;
 109                 vcpu->arch.pfault_select = parm.select_mask;
 110                 vcpu->arch.pfault_compare = parm.compare_mask;
 111                 vcpu->run->s.regs.gprs[ry] = 0;
 112                 rc = 0;
 113                 break;
 114         case 1: /*
 115                  * CANCEL
 116                  * Specification allows to let already pending tokens survive
 117                  * the cancel, therefore to reduce code complexity, we assume
 118                  * all outstanding tokens are already pending.
 119                  */
 120                 VCPU_EVENT(vcpu, 3, "pageref cancel addr 0x%llx", parm.token_addr);
 121                 if (parm.token_addr || parm.select_mask ||
 122                     parm.compare_mask || parm.zarch)
 123                         return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 124
 125                 vcpu->run->s.regs.gprs[ry] = 0;
 126                 /*
 127                  * If the pfault handling was not established or is already
 128                  * canceled SC24-6084 requests to return decimal 4.
 129                  */
 130                 if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
 131                         vcpu->run->s.regs.gprs[ry] = 4;
 132                 else
 133                         vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
 134
 135                 rc = 0;
 136                 break;
 137         default:
 138                 rc = -EOPNOTSUPP;
 139                 break;
 140         }
 141
 142         return rc;
 143 }
 144
 145 static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
 146 {
 147         VCPU_EVENT(vcpu, 5, "%s", "diag time slice end");
 148         vcpu->stat.instruction_diagnose_44++;
 149         kvm_vcpu_on_spin(vcpu, true);
 150         return 0;
 151 }
 152
 153 static int forward_cnt;
 154 static unsigned long cur_slice;
 155
 156 static int diag9c_forwarding_overrun(void)
 157 {
 158         /* Reset the count on a new slice */
 159         if (time_after(jiffies, cur_slice)) {
 160                 cur_slice = jiffies;
 161                 forward_cnt = diag9c_forwarding_hz / HZ;
 162         }
 163         return forward_cnt-- <= 0 ? 1 : 0;
 164 }
 165
 166 static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
 167 {
 168         struct kvm_vcpu *tcpu;
 169         int tcpu_cpu;
 170         int tid;
 171
 172         tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
 173         vcpu->stat.instruction_diagnose_9c++;
 174
 175         /* yield to self */
 176         if (tid == vcpu->vcpu_id)
 177                 goto no_yield;
 178
 179         /* yield to invalid */
 180         tcpu = kvm_get_vcpu_by_id(vcpu->kvm, tid);
 181         if (!tcpu)
 182                 goto no_yield;
 183
 184         /* target guest VCPU already running */
 185         tcpu_cpu = READ_ONCE(tcpu->cpu);
 186         if (tcpu_cpu >= 0) {
 187                 if (!diag9c_forwarding_hz || diag9c_forwarding_overrun())
 188                         goto no_yield;
 189
 190                 /* target host CPU already running */
 191                 if (!vcpu_is_preempted(tcpu_cpu))
 192                         goto no_yield;
 193                 smp_yield_cpu(tcpu_cpu);
 194                 VCPU_EVENT(vcpu, 5,
 195                            "diag time slice end directed to %d: yield forwarded",
 196                            tid);
 197                 vcpu->stat.diag_9c_forward++;
 198                 return 0;
 199         }
 200
 201         if (kvm_vcpu_yield_to(tcpu) <= 0)
 202                 goto no_yield;
 203
 204         VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: done", tid);
 205         return 0;
 206 no_yield:
 207         VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: ignored", tid);
 208         vcpu->stat.diag_9c_ignored++;
 209         return 0;
 210 }
 211
 212 static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
 213 {
 214         unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
 215         unsigned long subcode = vcpu->run->s.regs.gprs[reg] & 0xffff;
 216
 217         VCPU_EVENT(vcpu, 3, "diag ipl functions, subcode %lx", subcode);
 218         vcpu->stat.instruction_diagnose_308++;
 219         switch (subcode) {
 220         case 3:
 221                 vcpu->run->s390_reset_flags = KVM_S390_RESET_CLEAR;
 222                 break;
 223         case 4:
 224                 vcpu->run->s390_reset_flags = 0;
 225                 break;
 226         default:
 227                 return -EOPNOTSUPP;
 228         }
 229
 230         /*
 231          * no need to check the return value of vcpu_stop as it can only have
 232          * an error for protvirt, but protvirt means user cpu state
 233          */
 234         if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
 235                 kvm_s390_vcpu_stop(vcpu);
 236         vcpu->run->s390_reset_flags |= KVM_S390_RESET_SUBSYSTEM;
 237         vcpu->run->s390_reset_flags |= KVM_S390_RESET_IPL;
 238         vcpu->run->s390_reset_flags |= KVM_S390_RESET_CPU_INIT;
 239         vcpu->run->exit_reason = KVM_EXIT_S390_RESET;
 240         VCPU_EVENT(vcpu, 3, "requesting userspace resets %llx",
 241           vcpu->run->s390_reset_flags);
 242         trace_kvm_s390_request_resets(vcpu->run->s390_reset_flags);
 243         return -EREMOTE;
 244 }
 245
 246 static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
 247 {
 248         int ret;
 249
 250         vcpu->stat.instruction_diagnose_500++;
 251         /* No virtio-ccw notification? Get out quickly. */
 252         if (!vcpu->kvm->arch.css_support ||
 253             (vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
 254                 return -EOPNOTSUPP;
 255
 256         VCPU_EVENT(vcpu, 4, "diag 0x500 schid 0x%8.8x queue 0x%x cookie 0x%llx",
 257                             (u32) vcpu->run->s.regs.gprs[2],
 258                             (u32) vcpu->run->s.regs.gprs[3],
 259                             vcpu->run->s.regs.gprs[4]);
 260
 261         /*
 262          * The layout is as follows:
 263          * - gpr 2 contains the subchannel id (passed as addr)
 264          * - gpr 3 contains the virtqueue index (passed as datamatch)
 265          * - gpr 4 contains the index on the bus (optionally)
 266          */
 267         ret = kvm_io_bus_write_cookie(vcpu, KVM_VIRTIO_CCW_NOTIFY_BUS,
 268                                       vcpu->run->s.regs.gprs[2] & 0xffffffff,
 269                                       8, &vcpu->run->s.regs.gprs[3],
 270                                       vcpu->run->s.regs.gprs[4]);
 271
 272         /*
 273          * Return cookie in gpr 2, but don't overwrite the register if the
 274          * diagnose will be handled by userspace.
 275          */
 276         if (ret != -EOPNOTSUPP)
 277                 vcpu->run->s.regs.gprs[2] = ret;
 278         /* kvm_io_bus_write_cookie returns -EOPNOTSUPP if it found no match. */
 279         return ret < 0 ? ret : 0;
 280 }
 281
 282 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
 283 {
 284         int code = kvm_s390_get_base_disp_rs(vcpu, NULL) & 0xffff;
 285
 286         if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
 287                 return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
 288
 289         trace_kvm_s390_handle_diag(vcpu, code);
 290         switch (code) {
 291         case 0x10:
 292                 return diag_release_pages(vcpu);
 293         case 0x44:
 294                 return __diag_time_slice_end(vcpu);
 295         case 0x9c:
 296                 return __diag_time_slice_end_directed(vcpu);
 297         case 0x258:
 298                 return __diag_page_ref_service(vcpu);
 299         case 0x308:
 300                 return __diag_ipl_functions(vcpu);
 301         case 0x500:
 302                 return __diag_virtio_hypercall(vcpu);
 303         default:
 304                 vcpu->stat.instruction_diagnose_other++;
 305                 return -EOPNOTSUPP;
 306         }
 307 }